[Haskell-beginners] Data type

Hi, Could anyone please have a look and let me know how you can create the instance of this data type ? --- data Person = Person { firstName ::String -> Int } --- I've seen this type of syntax in a lot of places in haskell code where a new data type is defined in terms of functions rather than concrete data types. I am not trying to achieve anything out of this but purely as an exercise in understanding the record syntax. As far as I understand the data type is function based and takes a 'function' instead of a value of a concrete type so how does one create an instance of this type. Thanks, Shishir